For now, I'm just using the Canon bag that came with my camera when I bought it. It's got just enough room for my camera with the 18-55mm lens attached, as well as my 75-300mm, my charger, and the cable.
I've really been considering
one of these Vanguard bags. It will fit everything my current camera bag carries, and has a slot for my 15" laptop if I need to haul it as well. It also has an upper compartment that can be used for things like lenses and more camera gear, your phone, or whatever miscellaneous stuff that you might want to throw in a backpack as opposed carrying in your pocket. It also comes with a full rain cover that completely wrap around the backpack to keep rain and moisture out of your equipment. I'm also really liking the Pelican backpacks too because, well, Pelican.
I'm still honestly on the fence about spending that much money on something to carry my camera, but all the less expensive one's I've looked at online I just haven't really much cared for. Of the 30 or 40 I looked at on Amazon, this is about the only one that I really like in terms of how it carries the camera as well as being able to do double duty as a laptop bag. I also worry about the quality of something cheap not only in a longevity standpoint, but also in terms of how well it's going to protect my investment. I figure if I buy once, cry once and just spend some money on one, it'll last much longer and do a better job of protecting all my gear. As for why I want a backpack, I feel like I'll be much more inclined to take it places with me if it's in something that I can just throw on my back and go, than if it's in a bag that I have to carry on my shoulder and keep up with, which has been the case in the past. Not to mention the fact that I can throw whatever else in the backpack with it, and not have to worry about anything damaging my camera as it's in it's own compartment, so it'll will kind of double as a go-bag for when I hit the trails, camp, or just generally go anywhere.
I know. TL;DR